I remember reading that the minerals found in a strata most often are the ones that are not part of the recipe for making that theme. I suggest that the minerals found in boss strata NOT have this bias, since no minerals were actually used to construct them. The copper sun gate under construction is currently shock/poison/shock/poison/shock/poison, and I highly suspect that this is because of so many people doing Royal Jelly runs. If the influence of boss strata were to be removed, then maybe gates would become more varied.